The weekend bombings in New York and New Jersey and a stabbing spree in the Midwest are the latest example of the new terror threat faced by the United States along with much of the West: diffuse, unsophisticated and very hard to counter.

A tarmac tiff between U.S. and Chinese officials over media access highlighted the gap between views on human rights and press freedom, U.S. President Barack Obama said Sunday after the incident soured the start of a global summit.

Turkey's week-old cross-border operation in Syria could become a drawn-out affair that stokes tensions with Washington if Ankara continues to take the fight to U.S.-backed Kurdish fighters, analysts say.